The increase of CO2 in the atmosphere may produce some effects on drinking water because water tends to naturally capture CO2 species. The main purpose was the study of the impact of capture of free CO2 and its transformation to carbonic acid (H2CO3) and bicarbonate ions (HCO−3). The study used a Tillmans equilibrium diagram obtained from the modified Mojmir Mach model as a function of water temperature and considered the effects on anion and cation composition. Three wells located in different zones were selected, with similar characteristics (capture of CO2). Samples were taken in different seasons of the year and the amount of CO2 in the drinking water was calculated. It was found that with increasing concentrations of free CO2 the pH decreases, and this process makes the water acid and susceptible to dissolve some elements (Ca, Na, K, Si) and other species (HCO−3). The capture of CO2 has important effects on the anion and cation composition of drinking water and on the variation of pH by more than one unit, which may affect the health of consumers. The method presented in this study is an excellent user-friendly alternative to determine the impact of natural capture of total CO2 by water.